Unsettings is a graphical configuration program for the Unity desktop environment which lets you change some of Unity's settings. It also lets you save your settings into and load from a text file (in JSON format) so you can easily back up your settings or copy them to a different account.
WallShuffle allows you to regularly change your wallpaper. You select a folder, then select a duration to apply a random picture as a desktop background. You can start the program in minimized mode with the "-m" argument, if you don't want to see it, or even hide the icon from the tray and forget it.